Fertilizer application manual

Martin
Jan 5, 2024
2 min read

Subarea-specific N fertilization for grain

The aim is to specifically promote poorly developed plants/sections during the first fertilizer application and to promote well developed plants/sections during the last fertilizer application in order to increase the yield potential on the one hand and to supply all zones with nutrients as required on the other hand.

1. N-fertilizer application for grain

Heavy (clayey) areas warm more slowly in spring, are less reactive, and exhibit inhibited mineralization behavior -> red areas.

an aerial view of a wheat field showing a false color representation of the NDVI values — NDVI

an aerial view of a wheat field, which was divided into different zones depending on the clay content — Clay content (%)

Since less nitrogen is expected from the soil in the cold spring conditions, these areas need to be fertilized more heavily. Well-developed areas with adequate tillering should receive little encouragement, so these areas will receive less nitrogen.

Attention: a poorly developed stand can also occur due to a very sandy soil and a dry spring! The reason for this is inhibited mineralization due to lack of water, a stand compensation by an increased amount of fertilizer does not work here!

an aerial view of a barren field — Aerial view

an aerial photograph of the same field in NDVI false color representation — NDVI

These areas must be treated separately and quantities consistently reduced to also prevent overfertilization and possible nitrate leaching.

2. N-fertilizer application for grain

The aim of the 2nd fertilization is a further stand homogenization, if possible and reasonable. For the intervention in the stand density, the time is more decisive than the absolute level. The aim is a constant to moderate, variable fertilization.

3. N-fertilizer application for grain

At the time of the 3rd fertilization (EC39) there is the highest correlation to the later yield. Thus, it is possible to fertilize the amount of nitrogen still necessary for the expected yield and to achieve a balance.

The basis for the map generation of the 3rd fertilizer application is a current satellite image shortly before fertilization. Based on these index values, as already mentioned, the expected yield distribution and the nutrient requirement can be concluded.

The amounts fertilized so far are now subtracted from this total nutrient requirement and the remainder is to be applied during the last fertilizer application. In this way, considerably more fertilizer is applied to the very well developed areas, since the least fertilizer has been applied here so far due to the good development, but the requirement is highest due to the high yield expectation.

In the less developed sub-areas or on lower-yielding sites, the quantity can and should be reduced in a targeted manner, as there is no or little demand here.